interesting new problem

[servantsalesmen]

I just replaced my flexplate and got the truck running today! The truck has developed a shake/vibration at idle then again at 2200 rmp. I'm guessing it's torque converter. Any input? Also, the new flexplate is bigger and stiffer than oem. The truck cracked two oem flexplates at 35,000 miles each. My thought is that the new stiffer plate made the shake from the torque converter more pronounced.

[8.1HD/ALLISON]

Very possible. Remove and have balanced? Or checked.

[servantsalesmen]

What's the worst case if I let it go? Will it harm the tranny or the crankshaft? If it will hurt the trans, I'll leave it till it dies then replace the trans and converter. My hope is to build a performace truck out of it. Just crazy fast in a straight line lol

[8.1HD/ALLISON]

Hard to say. If bad enough it Could take crank and rear main out? Trans issues?

[servantsalesmen]

How would you define bad? In your opinion, how violent of a shake is really bad? I.E. a small vibration vs felling it in the seat vs the dash shaking vs. Steering wheel shaking vs. Consol shaking etc. I'm going to tackle it this weekend

[j-ten-ner]

I guess that any vibration caused by a rotating part is bad enough to be concerned.

And you don't know for sure where it comes from.

Could also be a bad spark plug or valve or camshaft or even the drive shaft. Or a low compression on one cylinder.

 

so long

j-ten-ner

[servantsalesmen]

I can rule most of those things out. It happens when the truck isn't moving. It's definitely either flexplate or torque converter. It seems to be worse in reverse though.

[8.1HD/ALLISON]

I can't describe a vibration. That's a seat of the pants thing. I'd say by your concern I wouldn't drive it.

[servantsalesmen]

Yup, I'm gonna pull her off the road this weekend. I'll post back with what I find. I have a feeling it could be the torque converter bolts. I had to sand them down on the heads just a hair to clear the bell housing (really stupid, I know) and I think that might have been enough to throw off the weight cause I'm sure they didn't all lose the same amount of weight.